Nutritional supplements are widely commercially available and are generally intended to supplement other nutritional sources. Currently available nutritional supplements include both emulsified supplements (generally “milk-based” supplements) and non-emulsified supplements (“clear” supplements). Many individuals today prefer to utilize clear supplements as they can provide a thin, good-tasting and refreshing means of supplementing energy, protein, vitamins and minerals.
An important nutrient in nutritional formulations is calcium. Calcium is the most abundant mineral in the body. Calcium is required for muscle contraction, blood vessel expansion and contraction, secretion of hormones and enzymes, and transmitting impulses throughout the nervous system. It is also important for bones and teeth health, where it supports their structure.
Another important supplement for nutritional formulations is beta-hydroxy-beta-methylbutyrate (HMB). HMB is a naturally occurring amino acid metabolite that is often formulated into a variety of nutritional products and supplements. HMB is commonly used in such products to help build or maintain healthy muscle mass and strength in selected individuals.
HMB is a metabolite of the essential amino acid leucine and has been shown to modulate protein turnover and inhibit proteolysis. In most individuals, muscle converts approximately 5% of available leucine to HMB, thus producing about 0.2 to 0.4 grams of HMB per day for a 70 kg male. In studies where various kinds of stress were induced in animals, HMB supplementation increased lean mass. Clinical studies also suggest that HMB has at least two functions in recovery from illness or injury including protection of lean mass from stress-related damage and enhancement of protein synthesis. It has been suggested that HMB may also be useful in enhancing immune function, reducing the incidence or severity of allergy or asthma, reducing total serum cholesterol and low density lipoprotein cholesterol, increasing the aerobic capacity of muscle, and other uses.
Since HMB is most often used in individuals to support the development and maintenance of healthy muscle mass and strength, many HMB products have been formulated with additional nutrients that may also be helpful in promoting healthy muscle. Some of these HMB products contain additional nutrients such as fat, carbohydrate, protein, vitamins, minerals and so forth. Calcium HMB is the most commonly used form of HMB when formulated into oral nutritional products, which products include tablets, capsules, reconstitutable powders, and nutritional liquids and emulsions.
It has been found, however, that substantially clear nutritional liquids containing protein, calcium HMB, along with supplemental calcium in some cases, are not physically stable over time as soluble calcium species present in the system can interact with intact proteins resulting in protein aggregation that results in sediment, gelation, and/or coagulation defects in the resulting product. This is especially true for acidified shelf stable liquid beverages subjected to high heat, such as that of a retort sterilization process, during manufacturing for microbiological control.
There is therefore a need for substantially clear nutritional liquids comprising calcium HMB, supplemental calcium, and proteins that remain physically stable during shelf life.